The present invention relates to an electrical contact and in particular to an electrical contact for receiving a complementary tab terminal.
It is well known to form an electrical connection between a tab terminal and a complementary electrical contact. One particular style of an electrical contact includes a base that has a bottom surface with two upstanding and opposing side walls from which contact arms are rolled over to form longitudinally extending contact surfaces above the bottom. When the tab is inserted into this type of electrical contact, it is positioned between the bottom and the contact surfaces. An example of a contact of this type is presented in EP 0 043 655. While it is advantageous that a contact of this type can be produced from a single piece of metal, the related contact forces during mating are occasionally undesirably high.
In order to improve upon contacts of this type, it is also known to form a contact having a pivoting contact spring mounted over a base with a bottom surface and two opposing side walls. The pivoting contact spring is typically a separate piece and coupled to the side walls such that a tab-receiving space is formed under the pivoting contact. An example of this type of contact is disclosed in GB 2 315 929. While a contact of this type has reduced insertion forces, manufacturing expenses are high due to the two-part construction.
While it is further known to form an electrical contact having a contact spring member disposed over a base that is formed with the base, as shown in U.S. Pat. No. 4,487,471, there are disadvantages associated with such a design. In particular, the terminal of this reference is only attached to the base along one side. When a mating tab is inserted, the attachment also flexes reducing contact effectiveness.
It would be desirable to improve upon the existing electrical contacts by providing an electrical terminal that avoids the disadvantages associated with the previous designs. It would be further desirable if the electrical contact could be adapted to prevent damage to or overstressing of the contact spring during insertion of the mating tab terminal. It would additionally be advantageous if the contact could be adapted with a locking member such that withdraw forces of the tab terminal are substantially larger than insertion forces. Finally, it would be advantageous if the electrical contact could be manufactured from a single piece of material.
An improved electrical contact according to the invention has a U-shaped base having a bottom and two opposing side walls that define a tab-receiving channel. The base has an open forward end for receiving a mating tab terminal and a rearward end with a middle region therebetween. A contact spring is disposed over the bottom and has a bridge which spans the bottom between the opposing side walls in the middle region of the base. A first contact arm extends from the bridge towards the forward end and converges towards the bottom to a first contact point and then diverges to a free end thereby defining a mating tab insertion mouth. A second contact arm extends from the bridge towards the rearward end and converges towards the base to a second contact point that is disposed closer to the base than the first contact point. The bridge is continuous with one of the opposing side walls and includes a free end that is attached to the other opposing side wall.
Additionally, tabs located along the side walls toward the forward end can extend out over the bottom such that the mating tab terminal is properly received so as to not damage the contact spring.
Toward the rear end, a further tab may be provided that overlies the contact spring and prevents overstressing of the spring. This tab may also advantageously be used to locate the electrical contact within the housing.
The second contact arm may include a tab terminal locating portion beyond the second contact point to prevent overinsertion of the mating tab terminal.
A locking protrusion may be provided on a spring arm within the bottom of the base, where the locking protrusion extends above the bottom for engaging a complementary feature in the mating tab terminal.